Ms Sanders’ partner Norman Busby, 86, was also stabbed in the chest, but survived the frenzied attack.

The retired policeman watched in horror as she was murdered by the intruder, who wielded a knife in each hand.

Ms Sanders’ family yesterday spoke of the devastation caused by McManus as he tried to steal the couple’s cars from their home in Crookston, Glasgow.

McManus, 20, blamed two other men for the bank worker’s death in April this year.

But a jury at the High Court in Glasgow took just over an hour to convict him of murder and attempting to murder Mr Busby.

McManus – who was 19 at the time of the attack – was also convicted of two other robbery-related stabbings.

He showed no emotion as the verdict was returned and was led to the cells.

McManus will be given a mandatory life sentence when he appears next month before judge Lord Armstrong who will set the minimum period.

Lord Armstrong told him: “This was a violent and vindictive murder of a woman in her own home and what was a cowardly attack on an 85-year-old man (now 86) who spent his life serving the community.”

Earlier it emerged McManus, of Glasgow, had boasted about appearing on television over the violent spree.

Ross Arthurs, 28, one of the former friends he blamed for the killing, said the thug told him: “I’m going to be on Crimewatch.”

McManus had lodged a special defence of incrimination, accusing Mr Arthurs and Christopher O’Reilly of the crime.

Both men denied being at Ms Sanders’ home on the night of the murder.

She fell to the ground covered in blood. I reached out but she was dead

Norman Busby

The Bank of Scotland employee was a keen church volunteer and helped out in a cafe at an old people’s home.

After she went to bed Mr Busby sat up playing Mahjong solitaire on his computer and completing a crossword.

The former police sergeant heard a knock on the front door and fearing a family member or neighbour needed help, answered it.

But McManus, who had targeted the property because the lights were on, barged in.

Mr Busby was stabbed “several times” in the chest before Ms Sanders came to the top of the stairs.

He said: “Isabelle screamed and ran down the stairs and she saw him standing there. I was lying on the floor covered in blood. She saw him stealing stuff and she tried to push him out the front door and he had his knives and he stabbed her several times.

“She fell to the ground covered in blood. I reached out but she was dead.”

He then pressed an alarm button they had in their house.

After seizing car keys from the house, McManus escaped, taking £300 in cash, a decanter filled with whisky and a laptop.

He failed to steal the couple’s Nissan Almera and left the bloody keys in the ignition before fleeing.

He went on a spending spree eight hours later, buying a tracksuit, a Celtic top and treating two friends to a Chinese meal. When tracked down by police, forensic tests found Ms Sanders’ DNA on his jogging trousers and top.

A week before the murder, McManus stabbed Ching Long Law, 19, as he tried to snatch his mobile phone. Despite suffering 12 wounds, Mr Law survived.

Two hours before killing Ms Sanders, he stole three bottles of Buckfast from a shop. He also tried to hijack a BMW 3 Series, stabbing its owner in the knee.

Outside court Ms Sanders’ family, including her brother James Dougall, said they had been left “devastated” and called for the “severe punishment” of her killer.

He added: “We would encourage everyone who agrees with this view to ensure their opinion is heard.”